Someone who is not a Redemptorist cannot be a transalpine Redemptorist, nor a modern Redemptorist, nor a traditional Redemptorist... nor a clever one either!

Up till now, the Holy See has used the name Redemptorist only for the members of the sole male Congregation founded by saint Alphonsus Maria de Liguori, the Congregation of the Most Holy Redeemer. Only them can be called Redemptorist Fathers or Brothers, or transalpine Redemptorists, if relevant.

If a member of the Congregation of the Most Holy Redeemer leaves the Congregation, then he is no longer a Redemptorist. Some have left to become secular priest, or to enter a monastic order, or another congregation... 

Any other congregation that indirectly calls its members Redemptorists or Transalpine Redemptorists would take the risk of deceiving its own members, their families, and the faithful. This deceit may stem from a refusal to face reality. No name is required to become a missionary.

You could use this name as a nickname, write articles on websites, or upload videos; this would not make you a Redemptorist. Window dressing might help change people’s minds about you, but it will not change what you really are — or are not. "No man is an island."

Real Redemptorists do not give nicknames to confreres. They do not take nicknames, the "Redemptorist" name speaks for itself, it is illustrious.